Pneumatic-despatch-tube apparatus.



1. T. NEEDHAM. PNEUMATIC DESPATCH TUBE APPARATUS.

APPLICATION FILED MAR. 27. 1908- Patented Apr. 24, 1917.

3 SHEETS-SHEET I.

J. T. NEEDHAM.

PNEUMATIC D ESPATCH TUBE APPARATUS. APPLICATION FILED MAR. 27, 1908.

1,223,414. 7 I Patented Apr. 24, 1917.

3 SHEETS-SHEET 2 W/T/VSSES i l/VI/ENT R g i 8;

' v @ATTORNEYS J. T. NEEDHAM.

PNEUMATIC DESPATCH TUBE APPARATUS. APPLICATION FILED MAR. 21. 1908.

1,223,414. Patented Apr. 24,1917.

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- ATTORNEYS the transmission tube; 1

mvrr D strA Es PATENT OFFICE.

JOHN T. NEEDI-IAM, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE LAMsoN ooM PA Y, oENEWAEK, NEW JERSEY, A CORPORATION or NEW JERSEY.

PNEUMATIC-DESPATCH-TUBE APPARATUS.

To all whom it-mag concern:

Be it known that I, JOHN T. NEEDHAM, a subject of the King of Great Britain, residing in the borough of Manhattan, city, county, and State-0t New York, have invented certain new and useful Improve ments in Pneumatic-Despatch-Tube Apparatus, of which the following is a specification, reference being had therein to the accompanying drawings, in which- Figure 1' is a diagrammatic view of the apparatus, the discharge terminals being in section; m

Fig. 2 a longitudinal vertical sectional view of the terminal at the distant end of Fig. 8 a plan view thereof, 1

Fig. 4: a longitudinal vertical sectional View of the terminal at the central station;

Fig. 5 a horizontal sectional view thereof on the line V-V of Fig. 1

Fig. 6 a vertical sectional view of the controlling valve taken on the line- VIVI of Fig. 7

Fig. 7 a valve; and v i Fig. 8 a vertical sectional view on the line VIII-VIII of Fig. 7. I a a This invention relates to improvements in that class of pneumatic despatch tube apparatus in' which air is exhausted from the despatch tubes the inrushing air serving to more the carriers therethrough; and it has for one of itsmain' objectsto provide a simple pneumatically operated means for controlling the movement of air through the tube, said controlling means being operated from the terminals and, at the introduction of a carrier into the tube.

Anotherobject of the invention is to -pro vide pneumatically operated means by which" Referring to the various parts by nu morals, 1 deslgnates a transmission tube; 2'

the exhaust drum or vacuum chamber con- Specification of Letters Patent.

receiving terminal at plan View :of the controlling v chamber 12 in which is secured obtained in nected thereto, and 3 the exhaust pump conminal at the distant end of the line; 6 the the distant end of the line; and 7 the discharge terminal at the central station. 8 designates the controlling valve'which is placed in the transmission tube near the exhaust drum and controls the passage of air from the transmission tube into said drum. When, the controlling valve is open air passes into the tube through the receiving terminal 4 at the central station, through the out-going member 1 of the transmission-tube and then back through the return member 1 of the transmission tube to the exhaust drum and then out through the exhaust pump. Both members of the transmission tube 1 and 1 are closed to prevent access of air therein except at the terminal. 4. The discharge terminal 5 at the distant end of the outgoing member of the tube is provided with a closure 9 which is adapted to be kicked-op en by the outgoing carrier. The receiving terminal 6 at the station at the distant end of the return member of -the transmission tube is provided with a normally closed gate 10 which is adapted to be opened by the operator when it is desired to send a carrier from said terminal to the central station. The discharge terminal at the central station is provided with a normally closed gate 11 which is adapted to be kicked open by the incoming carrier.

Secured in any suitable position adjacent the-gate 10 of the terminal 6 is a diaphragm a diaphragm 13. Connected to said diaphragm is an operating rod'14, the end of said rod being adj acent .the operating face of a cam 15 carried byj the gate 10 on the upper side thereof. Surrounding the operating rod 14 is a spring 16 whichnormally holds the said rod pressed forward against the cam 15, to hold the gate 10 closed and to hold the diaphragm 13 adjacent the inner wall of the diaphragm chamber. The diaphragm chamber 12 is connected to the controlling valve by a small tube 16 through which an impulse of air is sent by the diaphragm 13 when the gate 10 is opened. It will be readily understood that when the gate 10 is raised cam 15 will force Patented Apr. 24, 1917. H i Application filed March 27, 1908. Serial No.423, 527.

i the rod 14 inwardly thereby moving the diaphragm 13 toward the rear wall of the diaphragm chamber, forcing the air within said chamber through the tube 16. The air forced through said tube operates to open the controlling valve, as will be more fully hereinafter described.

Secured in any convenient position near the receiving terminal 4 is a diaphragm chamber 17 in which is arranged a diaphragm 18.

This chamber as shown is secured to the transmission tube, but, of course, it may be supported in any suitable manner. Gonnected to the diaphragm 18 is an operating pin 19 which is pressed forward by a spring 20. free end projecting into the transmission tube, is an operating lever 21. This lever is adapted to be forced outward by a carrier as it is inserted into the transmission tube through the terminal 4. The diaphragm chamber is connected to the controlling valve 8 by a tube 22 so that when a carrier is inserted in the terminal 4 an impulse of air is sent through the tube 22 to open the controlling valve.

The controlling valve 8 consists of a valve chamber 23 provided with the connections 24 and 25 to receive the transmission tube. Across the valve chamber is arranged a grid 26 over which is adapted to operate a grid valve 27. To the upper end of the valve chamber is connected a timing chamber 28 in the lower part of which are mounted two horizontal diaphragms 29 and 30, said diaphragms being spaced apart a suitable distance to form the chamber 31 between them. This chamber is in communication with the outer air through apertures 32 so that the adjoining sides of said diaphragms will be subject to atmospheric pressure. The lower diaphragm 30 is considerably smaller in area than the upper diaphragm 29, said diaphragms being rigidly connected together by means of a central spacing block 33. The lower smaller diaphragm 30 is connected to the grid valve by a stem 34 and a pin 35, whereby when the diaphragms are moved the grid valve will be correspondingly moved to open or close the valve, according to the direction of movement of the diaphragms. The chamber 36 below the diaphragm 30 is in communication with the exhaust side 25 of the valve chamber through an opening 37 so that said chamber will be subject to the exhausting action of the exhaust pump. The large vacuum timing chamber 38 above the upper and larger dia phragm 29 is in communication with the chamber 36 through a small by-pass passage 39, communication between said passages being regulated by a needle valve 40 so that the amount of air passing from the larger vacuum chamber 38 to the chamber 36 may be governed by said valve. It will, therefore Pivoted in any suitable position, its

be seen that both the chamber 36 and the chamber 38 will be at all times subject to the exhausting action of the pump 3 and that the same degree of vacuum will be maintained therein as is maintained in the exhaust drum, but that the chamber 31 between the two diaphragms will be subject merely to atmospheric pressure.

In the upper wall of the vacuum chamber 38 is arranged air inlet valve 41 mounted upon a pivoted, spring-pressed, arm or lever 42. Arranged in the upper wall of said chamber are two'diaphragms 43 and 44, said diaphragms extending across the small air chambers 45. The tube 16 from the diaphragm chamber 12 is in communication with the chamber 45 below the diaphragm 44; and the tube 22- is in communication with the chamber below the diaphragm 43. The lever 42 is operatively connected to or engaged by the diaphragms 43 and 44 by means of pins 46. It will be readily seen that when an impulse of air is sent through the tube 16 or tube 22 the corresponding diaphragm will be raised and the lever 42 carrying the air inlet valve 41 will be lifted, thereby permitting air to flow into the vacuum chamber 38.

Pivoted on the top of the timing chamber in a position to be engaged by the end of the lever 42'is a latch 47 which serves as a means for locking the lever in position to hold the valve 41 open. Secured to the chamber 38 adjacent to the latch 47 is a small diaphragm chamber 48 which is provided with a. flexible diaphragm 49, said diaphragm being connected to the latch 47 by a link 50. The diaphragm chamber 48 is connected by a small pipe 51 with the passage 39.

Arranged in a position to be engaged by the lever 42 when said lever is raised by one of the diaphragms 43 or 44 is a pair of contacts 52 which are in circuit with the motor starting solenoid of the motor 53. It will thus be seen that when the lever 42 is raised by either of the diaphragms 43 or 44 the motor will be set in operation to exhaust air from the exhaust drum and from the valve chamber. Arranged to be engaged by the core of the solenoid is a pair of contacts which will be brought into engagement with each other when the solenoid is raised to complete the motor circuit. These contacts are in circuit with the solenoid circuit so that they will complete the circuit through the solenoid winding without regard to the position of contacts 52.

The operation of the apparatus may be briefly described as follows Normally, for a given line of transmission tube connected to the drum or chamber 2, the grid valve 27 pertaining to such line is closed, and the diaphragms 29 and 30 are projected upwardly into the vacuum timing chamber. When an impulse of air is sent through eithertub'e 22 or tube 16 by the insertion ofca carrier in the terminal 4 or by a the lifting ofthe gate 10, the lever 42 will be lifted andthe air inlet valve4l opened.

The lever 42 will bring the contacts 52 together, thereby completing the circuit through the solenoid winding. When the circuit is completed the'motor will be started in the proper direction to exhaust air from the exhaust drum and transmission tube and the contacts 54'will be brought to:

gether, thereby completing the circuit a through the solenoid winding independently of the contacts 52 so that the latter contacts may separate when the valve 41 and thelever 42 are returned to their normal positions. The air pump or blower quickly exhausts air from the chamber 36 below the diaphragm 80, and as the timing chamber 38 is open to the atmosphere the diaphragms 29 and 30 will be moved downwardly valve.

When the lever 42 is moved upwardly by either diaphragm 43 or 44 the latch 47 is first moved outwardly away from the lever and then snapped under it to hold it in its raised position and to maintain the valve 41 open.v As soon as the exhaust pump is set in motion air is exhausted from the diaphragm chamber 48 through pipes 51 and 39. The exhausting of air from the diaphragm chamber 48 draws the diaphragm from one side of the casing to the other and moves the latch to release the lever42, thereby permitting the valve 41 to close. As soon to open the grid as valve 41 is seated the exhaust pump begins remain open until the proper degree of vacuum has been established in the timing chamber. The time required to secure this degree of vacuum may be regulated by the needle valve 40. -As soon as the proper degree of vacuum is established in the timing 'chamber 38 atmospheric pressure in chamber 31 acting on the differential diaphragms will raise said diaphragms and close the grid valve 27 When the valve 27 is closed it is desirable to stop the motor and exhaust pump if the vacuum inthe drum 2 is not longer required for carrier transmitting purposes through lines not shown as being merely repetitious of what has been shown. To accomplish this I provide a lever 55 pivoted between'the diaphragms 29 and 30 and arranged to be acted upon by the diaphragm 30 when the grid valve is raised to its closed position. One arm of this lever is extended beyond the valve casing and is adapted to engage and separate a pair of contacts 56, whereby said contacts will be separated when the valve 27 is closed. The contacts 56 are in circuit with the contacts 54 and with the solenoid winding. The circuit through the solenoid winding will be interrupted when the contacts 56 are separated noid core to drop to interrupt the motor circuit. In starting the apparatus the latch 47 will hold the lever 42 raised and the contacts 52 in engagement with each other until suflicient vacuum has been established in chamber 36 to secure the downward movement of the diaphragms and the valve 27. As soon as this movement of the diaphragms has been secured the contacts 56 will be in engagement and the solenoid circuit completed through said contacts before the lever 42 is released from the latch 47.

From the foregoing it will be seen that I provide an extremely simple pneumatic despatch tube apparatus of the vacuum type wherein the air exhausting mechanism is normally dead or at rest, and is set in motion when a carrier is placed in a given .transmission tube such as the one shown bv -tial parts of the apparatus. It will also be noted that I provide a vacuum system with a timing means or time element operated and controlled by exhausting air from a timing chamber. I also provide pneumatically operated means for starting the motor from the carrier-receiving terminals and means whereby the motor will be stopped when the proper degree of vacuum has been established in the timing chamber.

It will be readily understood that the diaphragms l3 and 18 will be returned to their normal positions as soon as the operating pins or bars have been released. .The vacuum in the chamber 38 will be destroyed every time a carrier is placed in the transmission tube so that carriers may be transmitted, one after theother, as rapidly as desired, the last carrier to be placed in the tube determining the length of time the controlling valve will remain in its open position. c

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1. A transmission tube, means for :exhausting air from said tube, a controlling valve to interrupt the passage of air through said tube, a vacuum chamber adjacent said valve and in communication with said tube, movable means'in said vacuum chamber and connected to the valve to close said valve when there is a partial vacuum in the vacuum chamber and to open said valve when the partial vacuum is destroyed, a venting valve for said vacuum chamber, pneumatic means for operating said venting valve, a receiving terminal for the transmission tube, a door for said receiving terminal, a small air tube extending from the receiving terminal to the pneumatic'means for operating the venting tube near the receiving terminal, a diaphragm in said chamber, means operated by the terminal door for moving said diaphragm to force air through said air tube to open the venting valve.

2. A transmission tube, means for exhausting air from said tube, a controlling valve to interrupt the passage of air through said tube, a vacuum chamber adjacent said valve and in communication with said tube, movable means in said vacuum chamber and connected to the valve to close said valve when there is a partial vacuum in the vacuum chamber and to open said valve when the partial vacuum is destroyed, a venting valve for said vacuum chamber, pneumatic means for operating said venting valve, a receiving terminal for the transmission tube, and means to set in motion the air exhausting means when the venting valve is opened.

3. A transmission tube, means for exhausting air from said tube, a controlling valve to interrupt the passage of air through said tube, a vacuum chamber adjacent said valve and in communication with said tube, movable means in said vacuum chamber and connected to the valve to close said valve when there is a partial vacuum in the vacuum chamber and to open said valve when the partial vacuum is destroyed, a venting valve for said vacuum chamber, pneumatic means for operating said venting valve, a receiving terminal for the transmission tube, and electrical means operated by the venting valve when said valve is opened to start the air exhausting means.

4. A transmission tube, means for exhausting air from said tube, a controlling valve to interrupt the passage of air through said tube, a vacuum chamber adj acent said valve and in communication with the air exhausting means, movable means in said vacuum chamber and connected to the valve to close said valve when there is a partial vacuum in the vacuum chamber and to open said valve when the partial vacuum is destroyed, a venting valve for said vacuum chamber, pneumatic means for operating said venting valve, a receiving terminal for the transmission tube, electrical means operated by the venting valve when said valve is opened to start the air exhausting means, means for holding closed the circuit of the electrical air exhausting means, a pneumatic means for releasing said holding means, said pneumatic means being connected to the air exhausting means whereby said holding means will be released when the air exhausting means is in full operation, and means operated by the controlling valve moving means to close the circuit through the air exhausting means when said controlling valve is open, said means opening said circuit and thereby stopping the air exhausting means when the controlling valve is closed.

5. A controlling valve for a pneumatic despatch tube apparatus comprising a valve adapted to close the transmission tube, a pair of parallel differential diaphragms connected to said valve and spaced apart to form a chamber between them, said chamber being open to the atmosphere, a vacuum timing chamber, the larger diaphragm forming one wall of said chamber, means for forming a chamber between the smaller dia phragm and the valve, said smaller chamber being in communication with the exhaust side of the valve chamber, means for placing said chamber in communication with the timing chamber, a valve for the timing chamber, and means for opening said valve.

6. A controlling valve for a pneumatic despatch tube apparatus comprising a valve chamber adapted to be connected to a trans mission tube formed with an inlet and an outlet, a valve therein, a pair of parallel differential diaphragms connected to said valve, the space between said diaphragms being subject to atmospheric pressure, a timing chamber, the larger diaphragm forming one wall of said chamber, the smaller diaphragm forming one wall of an exhaust chamber which is in communication with the outlet forming the valve chamber, and means for placing said exhaust chamber in communication with the timing chamber, a valve for the timing chamber, and means for opening said valve.

7. A controlling valve for a pneumatic despatch tube apparatus comprising a valve chamber adapted to be connected to a transmission tube provided with an inlet and an outlet, a valve therein, a pair of parallel differential diaphragms connected to said valve, the space between said diaphragms being subject to atmospheric pressure, a timing chamber, the larger diaphragm forming one wall of said chamber, the smaller diaphragm forming one wall of an exhaust chamber which is in communication with the outlet from the valve chamber, means for placing said exhaust chamber in communication with the timing chamber, a valve for the timing chamber, and pneumatically operated means for opening said valve.

8. A pneumatic despatch tube apparatus comprising a transmission tube, means for exhausting air therefrom, a controlling valve to close said tube and provided with a vacuum timing chamber, a valve for said chamber, a lever connected to said valve, a movable diaphragm operatively connected to said lever, means for sending an impulse of air pressure from the receiving terminal to move said diaphragm and thereby open the timing chamber valve, means whereby the controlling valve will be opened by the air exhausting means when the timing chamber valve is opened, and means whereby air is exhausted from the timing chamber and means whereby the controlling valve will be closed when the proper degree of vacuum is obtained in the timing chamber.

9. A pneumatic despatch tube apparatus comprising a transmission tube provided with receiving and discharge terminals, a blower connected to said tube and adapted to exhaust air therefrom, a motor fordriving said blower, a vacuum timing chamber in communication with the transmission tube, a movable means in said timing chamber adapted to be lifted when the proper de gree of vacuum is produced in said chamber, and to be lowered when the vacuum is destroyed, a venting valve for the vacuum chamber, means wherebysaid valve may be operated from the receiving terminalsin the transmission tube, a motor starting circuit including a pair of contacts adjacent the timing chamber, means whereby when'the venting valve is opened said contacts will be brought together and the motor starting circuit, completed, and means whereby when the proper degree of vacuumis produced in the timing chamber the movable means therein will interrupt the motor starting circuit and. thereby stop the motor. a

10.A pneumatic despatch tube apparatus comprising a transmission tube provided with receiving and discharge terminals, a blower connected to said tube and adapted to exhaust air therefrom, a motor for driving said blower, a vacuum timing chamber in communication with: the transmission tube, a movable means in said timing chamber adapted to be lifted when the proper degree of vacuum is produced in said chamber, and to be lowered when the vacuum is destroyed, a venting valve for the vacuum chamber, means whereby said valve may be operated from'the receiving terminals in the transmission tube, a motor starting circuit including a air of contacts adjacent the timing chani er, means whereby when the venting valve is open said contacts will be brought togetherand the motor starting circuit completed, and means whereby when the proper degree of vacuum is produced in the timing chamber the motor will be stopped, V a p I 11.- A pneumatic despatch tube apparatus comprising a transmission tube provided withreceiving and discharge terminals, an air exhausting means connected to said tube, a motor for operating said exhausting means,.a vacuum timing chamber in communication with the transmission tube, a diaphragm in said chamber adapted to be moved in one direction when the proper degree of vacuum is produced in said chamber, and to be moved in the opposite direction when the vacuum is destroyed, a venting valve for the vacuum chamber, means whereby said valve may be operated from the receiving terminals in the transmission tube,

means whereby when the venting valve is opened the motor will be started, and meansv whereby when the proper degree of vacuum s produced in the timing chamber the motor will be stopped.

'sion, tube and formed with an inlet and an outlet, a valve in said chamber, a pair of parallel differential diaphragms connected to said valve the space between said diaphragms being subject to atmospheric pressure, a timing chamber, the larger diaphragm forming one wall of said timing chamber, the smaller diaphragm forming one wall of an exhaust chamber which is in communication with the outlet from the valve chamber, means for placing the exhaust chamber in communication with the timing chamber, a venting valve for the timing chamber, means whereby said valve may be operated from the receiving terminals in the transmission tube, means whereby when the venting valve is opened the motor will be started, and means whereby when the proper degree of vacuum is produced in the timing chamber the controlling valve will be closed and the motor stoppe g ,13. A pneumatic despatch tube apparatus comprising a transmission tube, means for exhausting air therefrom, a controlling valve to close said transmission tube and provided with a vacuum timing chamber,

a pair of differential diaphragms connected to said valve, the larger diaphragm forming one wall of the timing chamber, the smaller diaphragm being subject to suction in the transmission tube, means placing the timing chamber in communication with the transmission tube, a venting valve for the timing chamber, whereby when the proper degree of vacuum is formed in the timing chamber the controlling valve will be closed, and when said vacuum is destroyed the suction on the smaller diaphragm will open said controlling valve.

14. A pneumatic despatch tube apparatus comprising a transmission tube, means for exhausting air therefrom, a valve to close said transmission tube, a pair of difierential diaphragms connected to said valve, and means whereby one of said diaphragms will operate to close the said valve and the other cwill operate to open said valve.

15..A controlling valve for a pneumatic despatch tube apparatus comprising a valve chamber adapted to be connected to a transmission tube, a valvetherein, a pair of difier'ential diaphragms connected to said valve, one of said diaphragms operating to close said valve and the other operating to open said valve.

16. A pneumatic despatch tube apparatus comprising a transmission tube, an air exhausting means, a valve to control the passage of air in said tube, a pair of differential diaphragms connected to said valve and subject to the influence of the air exhausting means, and means whereby ,one of said diaphragms will close said valve and the other will open said valve.

17. A pneumatic despatch tube apparatus comprising a transmission tube, an air exhausting means, a valve to control the passage of air through said tube, a pair of differential diaphragms connected to said valve and subject to the influence of the air exhausting means, and means whereby one of said diaphragms will close said valve and the other will open said valve, and means operated by said diaphragms for starting the air exhausting means when the valve is opened.

18. A pneumatic despatch tube apparatus comprising a transmission tube, an air exhausting means, a controlling valve arranged to close the transmission tube to prevent air moving therethrough, a pair of differential diaphragms connected to said valve and subject to the air exhausting means, a motor for operating the air exhausting means, and means whereby said motor will be stopped when the diaphragms are moved to close the controlling valve.

19. A pneumatic despatch tube apparatus comprising a transmission tube, an air exhausting means, a valve to control the passage of air through said tube, and means operated by the valve when it is moved to its closed position to stop the air exhausting means.

20. A pneumatic despatch tube apparatus comprising a transmission tube provided with receiving and discharge terminals, a blower connected to said tube and adapted to exhaust air therefrom, a motor for driving said blower, a vacuum timing chamber in communication with the transmission tube, a movable means in said timing chamber adapted to be lifted when the proper degree of vacuum is produced in said chamber, and to be lowered when the vacuum is destroyed, a venting valve for the vacuum chamber, means whereby said venting valve may be operated from the receiving termi nals in the transmission tube, a motor starting circuit including a pair of contacts adjacent the timing chamber, means whereby when the ventingvalve is opened said contacts will be brought together and the motor starting circuit completed, and means whereby when the proper degree of vacuum is produced in the timing chamber the movable means therein will interrupt the motor starting circuit and thereby stop the motor.

21. A pneumatic despatch tube apparatus comprising a transmission tube, an electrically operated air exhausting means, a pneumatically operated valve to control the passage of air through said tube, and electrical means operated by the valve when it is moved to its closed position to tend to stop the air exhausting means.

22. A pneumatic despatch tube apparatus comprising a transmission tube, an air exhausting means, a chamber between said tube and said air exhausting means, means operated by the insertion of a carrier to start the air exhausting means, a controlling valve normally closed, means operated by the insertion of a carrier to open said controlling valve and start the air exhausting means, meanswhereby the air exhausting means will close the valve, and means whereby the valve will stop the air exhausting means when said valve is moved to its closed position and when further flow of air through said chamber would be idle.

23. A pneumatic despatch tube apparatus comprising a vacuum chamber, a transmission tube adapted to be placed in communication with said chamber, a despatching station for said tube, means controlling said communication and normally closing the same to prevent any flow of air through said tube to said chamber when said tube is idle, a motor, air exhausting means operated by said motor and adapted to establish a partial vacuum in said chamber, and means controlled from said despatching station and co-acting with said first mentioned means to place said tube in communication with said chamber and to substantially simultaneously start said motor and air exhausting means into operation to establish a carrier transmitting flow of air through said tube.

24. A pneumatic despatch tube apparatus comprising a vacuum chamber, a transmis sion tube adapted to be placed in communication with said chamber, a despatching station for said tube, means controlling said communication and normally closing the same to prevent any flow of air through said tube to said chamber when said tube is idle, a motor, air exhausting means operated by said motor and adapted to establish a partial vacuum in said chamber, means controlled from said despatching station and co-acting with said first mentioned means to place said tube in communication with said chamber and to substantially simultaneously start said motor and air exhausting means into operation to establish a carrier transmitting flow of air through said tube, and time element means to co-act with said first mentioned means to limit the duration of said flow of air through the transmission tube aforesaid to a period determined by said time element means.

25. A pneumatic despatch tube apparatus comprismg a vacuum chamber, a transmission tube adapted to be placed in communication with said chamber, a despatching station for said tube, means controlling said communication and normally closing the 7 same to prevent any flow of air through said tube to said chamber when said tube is idle,

- a motor, air exhausting means operated by said motor and adapted to establish a par-t tial vacuum in said chamber, means controlled from the despatching station of said tube and co-acting with said first mentioned means to place said tube 1n commumcation' a carrier transmitting flow of air through said tube, and means to co-act with both said communication controlling means and motor to cause the former to closeand to tend to stop said motor when the flow of air] through the transmission tube aforesaid would be idle. I

26. A pneumatic despatch tube apparatus comprising a chamber, a transmission tube adapted to be placed in communication with said chamber, a despatching station for said tube, throttling means controlling said com munication and normally closed to prevent a flow of air through said tube when the latter is idle, a motor, air displacing means operated by said motor and adapted to cause a departure from atmospheric pressure in the air in said chamber, and means controlled from thedespatching stationofsaid tube and co-acting with a partof said throttling means to place said tube in communication with said chamber and to substantially simultaneously start said motor and air displacing means into operation to establish a carrier transmitting fiow of air through said tube.

27. A pneumatic despatch tube apparatus comprising a chamber, a transmission tube adapted to be placed in communication with said chamber, a despatching station for said tube, throttling means controlling said communication and normally closed to prevent a flow of air through said tube when the latter is idle, a motor, air displacing means operated by said motor and adapted to cause a departure from atmospheric pressure in the air in said chamber, means controlled from said despatching station of said tube and co -acting with a part of said throttling means to place said tube in communication with said chamber and to substantially simultaneously start said motor and air displacing means into operation to establish a carrier transmitting flow of air through said tube, and time element means vto co-act with said first mentioned means to limit the duration of said flow of air through the specified transmission tube aforesaid to a period determined by said time element means. a

28. A pneumatic despatch tube apparatus comprising a chamber, a transmission tube adapted to be placed in communication with a said chamber, a despatching station for said a tube, throttling means controlling said communication and normally closed to prevent a flow of air through said tube when the latter is idle, a motor, air displacing means operated by said motor and adapted to cause a departure from atmospheric pressure in the air in said chamber, means controlled from the despatching station of said tube and co-acting with a part of said throttling means to place said tube in communication with said chamber and to substantially simultaneously start said motor and air displacing means into operation to establish a carrier transmitting flow of air through said tube, and means to ,co-act with both said communication controlling means and motor to cause the former to close and to tend to stop said motor when the flow of air through a the specified transmission tube aforesaid would be idle.

, Intestimony whereof I hereunto afiix my signature, in the presence of two witnesses, this 20th day of March, 1908.

JOHN T. NEEDHAM.

Witnesses: WM. R. DAVrs,

E. H. H. KAUFMANN.

Copies of this patent may be obtained for fivecents each. by addressing the Commissioner of I'atents,

- Washington, D. 0. 

